SOUTH Korean rapper PSY's Gangnam Style has become YouTube's most viewed video of all time.

YouTube said in a posting on its Trends blog that Gangnam Style had been viewed 814 million times as of this morning, surpassing Justin Bieber's Baby, which has had 803 million views.

The blog says the "velocity of popularity for PSY's outlandish video is unprecedented". PSY's video featuring his horse-riding dance was posted on YouTube in July, while Baby was uploaded in February 2010.

PSY's video has become a global sensation, with many people around the world mimicking his Gangnam Style dance.

In their October meeting, United Nations secretary general Ban Ki-moon, a South Korean, joked that he had to relinquish his title as "the most famous Korean" and tried a few of PSY's dance moves.